Regulator for constant volumetric rate of gas flow



29, 1967 w. w. KENNEDY REGULATOR FOR CONSTANT VOLUMETRIC RATE OF GASFLOW 2 Sheets-Sheet l Filed Sept.

L/Afi 9% A TTORNEYS Aug. 29, 1967 w. w. KENNEDY REGULATOR-FOR CONSTANTVOLUMETRIC RATE! OF GAS FLOW 2 Sheets-Sheet 2 Filed Sept. 8, 1964INVENTOR.

h a/ar Kennedy BY United States Patent Ofi ice 3,338,265 Patented Aug.29, 1967 REGULATOR FOR CONSTANT VOLUMETRIC RATE OF GAS FLOW Walter W.Kennedy, Rockford, Ill., assignor to Barber- Colman Company, Rockford,111., a corporation of Illinois Filed Sept. 8, 1964, Ser. No. 394,967Claims. (Cl. 137-517) This invention relates to a regulator of the typedisclosed in Patent No. 3,049,146 for. automatically controlling theflow of gas through a duct by controlling the rolling of a flexiblecurtain onto and off from a perforated backing in response to changes inthe static pressure differential acting on an unsupported area of thecurtain and varying with changes in the supply pressure.

The primary object is to provide a regulator of the above characterwhich is much simpler and less expensive in construction than thepatented regulator.

A more detailed object is to control the rolling and unrolling of thecurtain by a member supporting the upstream end of the curtain andmovable along a fixed path extending transversely of the duct.

Another object is to provide a flow regulator of the above character inwhich said member is carried by the free' end of a swingable armprojecting downstream.

A further object is to utilize a simple contractile spring to providethe variable force for opposing the static pressure differential actingon the unsupported area of the curtain.

Other objects and advantages of the invention will become apparent fromthe following detailed description taken in connection with theaccompanying drawings, in which FIGURE 1 is a fragmentary longitudinalsection through a duct equipped with the improved flow regulator, thesection being taken along the line 11 of FIGS. 4 and 5 and showing thefull open position.

FIG. 2 is a similar sectional view showing the flow controlling curtainin closed position.

FIG. 3 is an enlarged view of a portion of FIG. 2.

FIG. 4 is a fragmentary plan section taken along the line 33 of FIG. 1.

FIG. 5 is a fragmentary perspective view with parts of one duct wall andthe curtain broken away.

As in the patented construction, the improved regulator is adapted tovary the flow passage through an intermediate cross-section of arectangular duct comprising parallel top and bottom walls and 11 andparallel side walls 12 and supplied with air under pressure through oneor more inlets 13. Said flow passage is defined at any given time by theuncovered area 14 of a screen or plate 15 extending transversely acrossthe duct and forming on its upstream face a backing for an imperforateand flexible curtain 16 which is rolled onto and oif from the perforatedarea of the plate to correspondingly vary the area of the flow passage.The perforations in the plate are sized to provide a large free air areaextending across substantially the full width and major depth of theduct between the inturned flanges 17 of plate 18 secured to the ductwalls and to the margins of the screen.

Preferably, the curtain 16 is a thin and flexible sheet of coated fabricrectangular in shape and extending substantially across the full widthof the duct. One end of the curtain is secured as by a clamping bar 20against the upstream face of the upper flange 17 and along a transverseline paralleling the upper and lower duct walls. To utilize the pressureof the oncoming air most effectually in sealing the side edges of thecurtain against the upright flanges 17, the backing between the line ofattachment of the curtain and the lower wall of the duct is preferablyinclined to provide a slightly obtuse angle between the screen and thebottom duct wall on the upstream side of the screen.

In accordance with the present invention, the free edge 21 of thecurtain is secured to a member 22 which is movable in a path 23extending transversely of the duct and disposed relatively close .to thescreen near the bottom wall of the duct at its lower end. The pathextends upwardly and away from the screen to a point about midwaybetween the top and bottom walls of the duct where the free edge of thecurtain will be spaced a substantial distance from the screen as shownin FIG. 1, this being the position of maximum uncovering of the screen.

Herein, the path 23 is arcuate and defined by the free end of anelongated arm or yoke projecting downstream from a fulcrum axis 25spaced upstream a substantial distance from the screen and near thebottom wall 11 so that the arm is disposed substantially horizontallywhen the curtain is in the position of maximum coverage of the screen asshown in FIG. 2. The yoke arm is formed by two elongated bars 24 lyingadjacent the side walls 12 and pivoted at their upstream ends on pins 27which define the fulcrum 25. At their downstream ends, the arms arespanned and rigidly joined by a cross-member 22 around which the freeend of the curtain, as indicated at 29 (FIG. 3), is looped and suitablysecured as by adhesive between the overlapping areas.

A simple contractile spring 30 is connected at one end to the center ofa bar 31 and disposed intermediate the ends of the side arms 24. Theopposite end of the spring is fixed to the center of a bar 32 extendingacross the top wall of the duct, the spring being tensioned to peel thecurtain off from the screen 15 and to exert its greatest force when themember 22 is in the position of minimum opening (FIG. 2) determined by astop 33. The latter is located in a position which, as shown in FIGS. 2and 3, prevent complete covering of the outlet area 14 for a reason topresently appear.

By spacing the path 23 of swinging of the cross-bar 22 upstream from thescreen 15, it will be apparent that the free and unsupported end portionof the curtain, in the different vertical positions of the cross-bar,will project upstream and away from the screen as shown in FIGS. 1 and 2and cooperates with the side walls 12 and the top and bottom walls 11 todefine upper and lower chambers 35 and 36. The upper chamber is closedat its downstream end by the upper flange 17 and the end portion of thecurtain lying against and covering the screen 15. Thus, the pressure inthis chamber is always equal to the static pressure of the air deliveredinto the duct through the inlet 13.

The downstream end of the lower chamber 36 is defined by the uncoveredscreen openings which, being of lesser area than the upstreamcross-section of the duct, constitute an orifice or restriction whichvaries in area according to the extent of unrolling of the curtain fromthe screen. The increase in the velocity of the flow through thisorifice as compared to the velocity at the duct inlet results in a lowerstatic pressure in the lower chamber 36. A pressure differential is thusexerted on the unsupported or dividing portion of the curtain in adirection to reduce the size of the uncovered area of the screen. Thisdifferential is balanced against the force of the spring 30 so that, asin the patented construction, the extent of peeling of the curtain 16away from the screen 15 will vary inversely with the inlet air pressureand the size of the restricted flow area 14 will be adjustedautomatically with changes in this pressure to maintain a substantiallyconstant rate of flow in spite of variations in the supply pressure.

To make the pressure in the upper chamber 35 accurately follow thechanges in the inlet pressure, an imperforate bafile plate 38 spacedupstream from the curtain is positioned to intercept the incoming airand divert a portion thereof upwardly toward the chamber 35. This plateis substantially flat, is inclined upwardly toward the chamber 35 andoccupies an area at the center of the duct which is a small fraction ofthe cross-section of the duct. It is secured to a cross-bar 40 extendingacross the duct with opposite ends fixed to the duct side walls 12.

By supporting the free edge of the curtain on the pivoted arm 24 whosemotion is controlled by a contractile spring, an exceedingly simple andinexpensive construction has been provided to compensate automaticallyfor changes in the pressure of the suppliedair and maintain at all timesa constant rate of flow through the duct.

I claim as my invention.

1. The combination of, a duct of rectangular crosssection adapted forthe forced flow of air therethrough in one direction, a rigid plateextending across the full crosssection of the duct and having aperforated area adjacent one wall of the duct, means defining a pivotextending transversely of said duct and spaced upstream from said plate,an elongated arm fulcrumed on said pivot and projecting downstreamtherefrom with its free end disposed opposite but short of saidperforated area, an elongated flexible and rectangular curtain securedat one end to said free arm end and at the other end to said plate forflexing and covering areas of the perforations which increase anddecrease as the arm swings across the perforated area and toward andaway from one wall of the duct, said curtain cooperating with the wallsof said duct on the opposite side thereof to define a chamber openingupstream but closed at its downstream end to create a drop between thestatic pressures in such chamber and the upstream side of saidperforated area, and yieldable means continuously urging said arm ina'direction to unroll said curtain and expose a greater area of theperforations as said pressure drop decreases with a decrease in thepressure of the air supplied to the inlet end of said duct.

2. A flow regulator as defined in claim 1 in which the path of movementof said free arm end converges toward said perforated plate area wherebythe effective area of said curtain defining the inner wall of saidchamber decreases progressively during movement of the member to closesaid flow passage.

3. A flow regulator as defined in claim 1 in which said yieldable meansis a contractile spring stretched between said arm and the outer wall ofsaid pressure chamber.

4. An air flow regulator as defined in claim 1 in which said swingablearm comprises a U-shaped yoke substantially corresponding in width tosaid duct.

5. An air flow regulator as defined in claim 1 including a bafilesmaller in cross-section than said duct and positioned to intercept aportion of the air stream delivered through said duct inlet and deflectthe same laterally of the duct and toward the inlet of said pressurechamber.

References Cited UNITED STATES PATENTS 3,049,146 8/1962 Hayes 137-517WILLIAM F. ODEA, Primary Examiner. H. M. COHN, Assistant Examiner.

1. THE COMBINATION OF, A DUCT OF RECTANGULAR CROSSSECTION ADAPTED FORTHE FORCED FLOW OF AIR THERETHROUGH IN ONE DIRECTION, A RIGID PLATEEXTENDING ACROSS THE FULL CROSSSECTION OF THE DUCT AND HAVING APERFORATED AREA ADJACENT ONE WALL OF THE DUCT, MEANS DEFINING A PIVOTEXTENDING TRANSVERSELY OF SAID DUCT AND SPACED UPSTREAM FROM SAID PLATE,AN ELONGATED ARM FULCRUMED ON SAID PIVOT AND PROJECTING DOWNSTREAMTHEREFROM WITH ITS FREE END DISPOSED OPPOSITE BUT SHORT OF SAIDPERFORATED AREA, AN ELONGATED FLEXIBLE AND RECTANGULAR CURTAIN SECUREDAT ONE END TO SAID FREE ARM END AND AT THE OTHER END TO SAID PLATE FORFLEXING AND COVERING AREAS OF THE PERFORATIONS WHICH INCREASE ANDDECREASE AS THE ARM SWINGS ACROSS THE PERFORATED AREA AND TOWARD ANDAWAY FROM ONE WALL OF THE